1. Technical Field of the Invention
The present invention relates in general to string and blade trimmers and the rotating heads of such trimmers. More specifically, the present invention provides a two-mode convertible trimmer head having in a first mode outwardly extending monofilaments and in a second mode outwardly extending blades, all for cutting vegetation when the monofilaments or blades are rotating in a cutting plane. Both the blades and the monofilament lines of the trimmer head are replaceable by the user without the use of tools.
2. Description of the Related Art
Vegetation trimmers are well known devices used to cut weeds, grass, and other vegetation. The vegetation trimmer, or simply “trimmer”, generally comprises an elongated handle assembly having one or more handgrips and a power source proximate to the upper end, and a rotating trimmer head proximately mounted at a lower end. The trimmer head generally comprises one or more radially outwardly extending flexible monofilaments or pivotally mounted blades. As the trimmer head is rotated by the power source at a high rotational velocity, the blade(s) or monofilament(s) are spun in a cutting plane for shearing grass, weeds, and the like. The rotational power is generally is supplied by a gas or electric motor. Many versions of these trimmer devices are known and many improvements have been made over the years.
While monofilament based trimmer heads are appropriate for edging and for cutting grass, weeds, and other light vegetation, a growing number of trimmer heads have incorporated rigid, pivotally mounted blades made of plastic, metal, a combination thereof, or other suitable components. These blades offer the advantage of allowing a trimmer to cut thicker, tougher, woody vegetation such as saplings and low bushes that monofilament heads cannot. Though such blade-based trimmer heads offer clear advantages, there are drawbacks including increased torque requirements, a decreased radius of the cutting plane, reduced grass cutting efficiency as the blades dull over time, and increased risk of the trimmer flinging small objects at high velocity (rocks, bits of wood, etc.) at people, pets or other objects. Blades also cannot be used against a curb, fence, or other hard surface, which makes them impractical for edging. Finally, blades do not benefit from the self-replenishing mechanisms that automatically (or in the case of bump and feed trimmers, manually during use) dole out additional trimmer line. With blades, the user must completely stop the motor and through the use of a tool manually is remove the worn blades and install new blades.
Because there are distinct advantages and disadvantages to both monofilament string and blade-based trimmer heads, it is often advantageous for the user to have both. When both are used, each may be used in an area where its strengths are maximized. The downside to this approach is that it necessitates the need to have two separate trimmer heads on hand, one configured for use with monofilament line and another configured for use with blades. Further, the user must change the trimmer head attached to the trimmer, a process which often takes much of the user's time, requires the use of tools, and depending on the complexity of the task and the skill of the operator is oftentimes difficult to accomplish. The ownership of multiple trimmers, each equipped with a different trimmer head can be economically impractical, and requires additional space for storage and time for maintenance.
It is thus desirable to provide a trimmer head that has both a blade trimming mode and a monofilament-trimming mode. Most attempts at such a two mode trimmer head have required the complex disassembly and reassembly of the trimmer head. These operations are time consuming, require tools, and may be technically complex.
Hence, it can be seen that there is a need for an improved two-mode trimmer head. Such a device should not require tools to change the trimmer heads, thus requiring minimal time and effort to change between the two modes. There should also be no need to use tools to replace broken monofilament or blades, resulting in less complexity and requiring minimal time and effort for such replacement. The current application discloses the novel changes to the two-mode trimmer head, which result in these improved efficiencies.